How to convert a FULL Join to a subquery in SQL?

I have a SQL query as follows:

SELECT DISTINCT FirstName, LastName
FROM Students FULL JOIN 
        AssignmentSubmissions
        ON Students.Id = AssignmentSubmissions.StudentId
WHERE AssignmentSubmissions.StudentId IS NULL;

I a trying to figure out a way to form an equivalent subquery. But since the comparison operator is NULL here for AssignmentSubmissions.StudentId I am not able to come up with a solution.

>Solution :

a) Not sure why you’ve got a FULL JOIN here rather than LEFT OUTER JOIN – it appears that a LEFT OUTER JOIN is more appropriate.

SELECT DISTINCT FirstName, LastName
FROM Students 
    LEFT OUTER JOIN AssignmentSubmissions
        ON Students.Id = AssignmentSubmissions.StudentId
WHERE AssignmentSubmissions.StudentId IS NULL;

b) If you don’t want to use a JOIN, you can use a WHERE clause e.g.,

SELECT DISTINCT FirstName, LastName
FROM Students 
WHERE Students.Id NOT IN (SELECT StudentId FROM AssignmentSubmissions);

However, this doesn’t really save you anything (it may even have the same execution plan) – why do it?